Java has a type and effect system. Methods return type * effect - this causes problems, a big one in Java is that effects can't be polymorphic.
Anyway, I wouldn't like to see an effect system in Haskell (though, seems like Scala is getting one). We already express IO and State as a type. How about we express exceptions as types? Easy:
Anyway, I wouldn't like to see an effect system in Haskell (though, seems like Scala is getting one). We already express IO and State as a type. How about we express exceptions as types? Easy:
http://hackage.haskell.org/packages/archive/mtl/1.1.0.2/doc/...